For a Low Temperature Poly-Silicon (LTPS) based Active Matrix Organic Light-Emitting Diode (AMOLED) pixel driving circuit, since the LTPS has a problem of poor threshold voltage uniformity, in the pixel design of AMOLED, it requires to add a circuit that compensates for a threshold voltage of a driving thin film transistor (TFT).
As shown in FIG. 1A, a common design of an AMOLED pixel driving circuit having a threshold voltage compensation function requires a 6T1C pixel driving circuit, or requires more TFTs and/or capacitors. As shown in FIG. 1A, the 6T1C pixel driving circuit comprises a first control transistor T1, a second control transistor T2, a third control transistor T3, a fourth control transistor T4, a fifth control transistor T5, a storage capacitor Cs and a driving transistor DTFT, and is configured to drive an organic light-emitting diode OLED; gate electrodes of T1, T3 and T4 are connected to a first scan voltage VSCAN1, gate electrodes of T2 and T5 are connected to a second scan voltage VSCAN2, T1 is further connected to a data voltage Vdata, a first terminal of Cs is marked as A, a second terminal of Cs is marked as B, a node connecting T2, T3 with a gate electrode of DTFT is marked as C, an anode of OLED is connected to a high level VDD, and one terminal of T5 is connected to a low level VSS.
As shown in FIG. 1B, the existing pixel circuit comprises L rows of pixel units, each row of pixels units comprises M 6T1C sub-pixel units, and each 6T1C sub-pixel unit comprises a 6T1C pixel driving unit and a light-emitting element, where L and M are positive integers greater than 2, n is a positive integer greater than 1 and smaller than L, and n is smaller than M, Gate_1 is a first gate line, Gate_n−1 is an (n−1)-th gate line, Gate_n is an n-th gate line, Gate_L is an L-th gate line, Data_1 is a first data line, Data_n−1 is an (n−1)-th data, Data_n is an n-th data line, and Data_M is an M-th data line.
In the related art, the number of TFTs and/or capacitors would be increased due to the need of compensation for the threshold voltage, such that more control signals are required and a larger wiring space is occupied, which is disadvantageous for the reduction of AMOLED pixel size, i.e., limiting development of the AMOLED pixel driving circuit having a high PPI (Pixel per Inch).